Realizing Highly Reversible Zinc Anode via Controlled-current Pre-deposition

Aqueous zinc ion batteries have been considered as the prominent candidate in the next-generation batteries for its low cost, safety and high theoretical capacity. Nonetheless, formation of zinc dendrites and side reactions at the electrode/electrolyte interface during the zinc plating/stripping process affect the cycling reversibility of the zinc anode. Regulation of the zinc plating/stripping process and realizing a highly reversible zinc anode is a great challenge. Herein, we applied a simple and effective approach of controlled-current zinc pre-deposition at copper mesh. At the current density of 40 mA cm(-2), where the electron/ion transfers are both continuous and balanced, the Zn@CM-40 electrode with the (002) crystal plane orientation and the compactly aligned platelet morphology was successfully obtained. Compared with the zinc foil, the Zn@CM-40 exhibits greatly enhanced reversibility in the repeated plating/stripping (850 h at 1 mA cm(-2)) for the symmetric battery test. A series of characterization techniques including electrochemical analyses, XRD, SEM and optical microscopy observation, were used to demonstrate the correlation between the structure of pre-deposited zinc layer and the cycling stability. The COSMOL Multiphysics modeling demonstrates a more uniform electric field distribution in the Zn@CM than the zinc foil due to the aligned platelet morphology. Furthermore, the significant improvement is also achieved in a Zn||MnO2 full battery with a high capacity-retention (87% vs 47.8%). This study demonstrates that controlled-current electrodeposition represents an important strategy to regulate the crystal plane orientation and the morphology of the pre-deposited zinc layer, hence leading to the highly reversible and dendrite-free zinc anode for high-performance zinc ion batteries.

Automated summary

This study applied a simple and effective approach of controlled-current zinc pre-deposition at copper mesh, resulting in a highly reversible and dendrite-free zinc anode for high-performance zinc ion batteries. The pre-deposited zinc layer with (002) crystal plane orientation and compactly aligned platelet morphology exhibited significantly enhanced cycling stability compared to zinc foil. Moreover, a significant improvement in capacity-retention was also achieved in a Zn||MnO2 full battery.